Laptop won't wake from sleep with the lid closed on a dock, what should I check?

Closed lid plus dock adds the dock to the sleep and wake path. Set the lid action to Do nothing, then use powercfg to see what woke or blocked the last sleep. Allow only the keyboard to wake the machine, update the dock, BIOS and graphics drivers, and test again.

Run these in an administrator Terminal or Command Prompt, straight after a bad wake. Microsoft's powercfg documentation describes them: /lastwake reports what woke the system from the last sleep transition, /devicequery wake_armed lists devices currently configured to wake the system, /requests lists application and driver power requests that prevent the computer from sleeping, and /waketimers lists active wake timers. If the dock or a network adapter shows up as a wake source, you can limit it with /devicedisablewake for a specific device name, or in Device Manager, on the device's Power Management tab.

Next, drivers. Dell's troubleshooting guide lists outdated drivers for chipset, BIOS and docking stations among the causes of performance problems, and recommends disconnecting devices such as docking stations to find out whether the fault is the computer or the dock. It is not a sleep article, so borrow the method: unplug the dock for a day, use the laptop on its own screen, and see if the problem disappears. If it does, update the dock firmware from your laptop maker's support page.

Dmitri, turning off Fast Startup is a fine test but it is not a universal cure, and it does not address a dock that does not signal the monitors on wake. The earlier sleep thread has the rest of the list, including the Windows key, Ctrl, Shift and B reset for a display that stays black. Menu names differ between Windows 10 and 11, so check the version first.